Technical systems, such as machine tools and industrial robots, for example, harbor the risk of injury to persons approaching the movable parts of the machine. Hazardous areas around a reel changer include particularly the pivoting region of the reel support arms, the area behind the reel changer in the pivoting region of the splicing frame, the loading area, and the pit below the reel changer, if provided. It is therefore necessary for machines to be provided with safety devices, which prevent injuries to persons caused by the working movement of the movable parts of the machine. In the past, primarily mechanical safety devices have been employed for this purpose. For instance, machine tools are frequently completely enclosed, with access being allowed via safety gates. Industrial robots are operated in areas enclosed by protective fencing.
However, mechanical safety devices are associated with disadvantages. Adequate space must be provided for the safety device itself and for the opening of any safety gates that may be present, which increases the amount of space needed for the entire system. Moreover, rapid intervention into the production sequence is not possible, as opening safety gates or protective fencing requires a corresponding amount of time and control. Furthermore, mechanical safety devices are not maintenance and wear free.
DE 10 2005 048 466 A1 describes a personnel safety device on a reel changer of a printing press, which is embodied, for example, in the form of a catch net on the loading side of the reel changer. This safety device is embodied to turn the loading side into a secured area whenever the residual paper reel approaches a critical diameter, i.e., is at risk of breaking. Persons near the reel changer are thereby to be reliably protected from fragments of bursting reels. For this purpose, the safety device is mounted on the transfer table that is used to supply new reels of material, and at a fixed point in relation to the reel stand on the loading side. To supply a new material reel, the transfer table moves up to the reel stand, thereby setting up the safety device. Therefore, the safety device is activated only when the described critical status of the residual paper reel is reached. At all other times, the area on the loading side of the reel changer can be accessed unimpeded. However, to inform persons present in the potentially hazardous area of the potential hazard even when the mechanical safety device is inactive, an additional securing of the area using photoelectric beam interruption detectors is proposed. On the basis of the signal emitted by the beam interruption detector, a visible or audible signal for a person present in the area of the reel changer is emitted.
From WO 2005/080241 A2 it is known to provide a zone safety device in the area surrounding large moved reels of material for purposes of occupational safety. In this case, the erection of fencing along the boundaries of a material reel storage area is proposed. To allow material reels to be transported into and out of the storage area, a lock can be provided in the zone safety device. In the lock area, a preferably contactless zone safety device is proposed, which can be implemented as photoelectric beam interruption detectors or ultrasonic sensors, for example. By arranging sensors of this type at different levels, complex sensing routines can be implemented, so that, for example, reels of material are allowed to pass through the lock without problems, whereas any unauthorized passage through the sensor areas will trigger an alarm and/or will halt the movement of the material reels, in order to prevent accidents.
EP 08 49 201 A1 relates to a method for detecting lateral position and for positioning a reserve web reel, wherein reel thickness and the respective lateral distance from the reel changer are measured and evaluated by directly opposite scanning elements in the form of sensors, for example, laser beam or ultrasonic sensors. Moreover, the scanning elements are connected to a programmable control system for a drive unit for positioning the spare web reel.
EP 15 93 630 A2 discloses a device for preparing a web of material wound onto a spare reel, which has a bearing for supporting and rotating the spare reel about a longitudinal axis. Sensors detect the radius of the spare reel during rotational movement. A plurality of sensors for detecting the radius are arranged parallel to the longitudinal axis of the spare reel.
The contactless devices described in the aforementioned publications serve to detect the positioning or the dimensions of a reel in the region surrounding the automatic loading of reels on a reel changer, and serve no safety or protective function.
From DE 31 34 815 C2, a contactless area safety system, for example, for securing or monitoring viewing windows is known. The area safety system has a source which emits radiation over its entire length, along one side of the area to be secured. Along the opposite side, a reflective strip is provided. The radiation is predominantly reflected in the plane spanned by the source and the reflective strip. At each end of the radiation source, a radiation detector is provided, which is connected to an evaluation circuit. This area safety system can be used as security against passage, for example, through hazardous areas by installing a multiple infrared beam barrier between two rods, which, when interrupted, triggers a signal. The disadvantage of this system for securing hazardous areas is that it is able to perform only a simple protective function.
From DE 199 38 639 B4, a device for securing a hazardous area, particularly the hazardous area of an automatically operating machine, is known, said device comprising first means for generating an optically monitored virtual barrier and second means for generating a switching command to stop the machine when a barrier is penetrated. The first means has an image recording unit and a defined target, the image of which is recorded by the image recording unit and compared by a comparison unit (second means) with a size which is characteristic for a reference image. The defined target is a structured, high-contrast pattern, which contains positioning marks for determining a current position. Using a point pattern, according to one embodiment example of the device, a virtual barrier can be generated, the shape of which corresponds approximately to that of a beam interruption detector. Alternatively, however, a plurality of point patterns can be placed in a row to generate a linear pattern. This device performs only a protective function. The evaluation and the comparison of the recorded images with the reference image are costly.
DE 296 02 098 U1 relates to a reel changer in a web-fed rotary printing press for loading a web of print substrate wound onto reels into a printing couple of the web-fed rotary printing press. The area surrounding the reel changer is monitored by at least one sensor, particularly an optical sensor, for example, a camera, which is connected to an image recognition computer. In the image recognition computer, a comparison is made between a recorded actual image of the area and a stored set image or a sequence of set images. In the event of deviations, a signal generating device generates a warning or alarm signal. The at least one sensor can also be assigned contact mats, contact strips, photoelectric beam interruption detectors, or similar contactless safety devices, which supply partial information or control or activate the sensor. The solution disclosed in this publication enables a monitoring of the region surrounding the reel changer, whereby selective protection is realized in that known objects are recognized and the entry thereof into the area without triggering warning or alarm signals is enabled. However, image recognition can be easily influenced by subjective factors in the monitored area, for example, a deviation in position of an object, which is to be recognized as known in the set image, on a recorded actual image, which can lead to disruptions or malfunctions.
DE 100 26 305 A1 describes an optoelectronic device for monitoring a protected area with at least one contactless safety device, which has an evaluation unit for generating an object detection signal when an object enters the protected area. The contactless safety device can be a light beam barrier, which comprises a transmitter unit which transmits light beams, a receiver unit which receives the light beams, and an evaluation unit connected to the receiver unit. To perform another function in addition to the protective function, the contactless safety device is coupled with an image recording unit for sensing a secondary monitoring area, which lies close to the protected area but outside of the protected area. This so-called muting function allows the short-term deactivation of the contactless safety device, to allow recognized objects to enter the protected area without generating an object detection signal. The muting function is implemented by the image recording unit, which detects the objects that enter the secondary monitoring area, wherein differentiation is made between permissible and impermissible objects. The detected objects may be classified. The disadvantage of this solution is that the recognition of known objects does not always function reliably. In addition, the setup of an additional image recording unit involves additional complexity and financial expense.
From DE 10 2005 030 829 A1 a method for operating a multiple infrared beam barrier is known, in which a switching signal is generated from the sequential interruption of the light beams with a stored reference profile.
DE 10 2004 038 906 A1 proposes transmitting a mark on an object to an evaluation unit, in addition to a multiple infrared beam barrier.
In DE 295 00 873 U1 the sequence of interruption of the light beams of a multiple infrared beam barrier is detected, in order to distinguish between permissible objects and persons, for example.